Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
  • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
  • H01M50/42—Acrylic resins
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to an aqueous resin composition for a lithium ion secondary battery separator heat-resistant layer binder.
• a separator used for manufacturing a lithium ion secondary battery in general, a porous body obtained by using a polyolefin resin or the like is often used.
• a lithium ion secondary battery usually exhibits a function as a battery by moving ions in an electrolytic solution through holes constituting the separator.
• the lithium ion secondary battery may cause ignition or the like due to abnormal heat generation.
• a method for preventing the ignition or the like for example, a method using a separator in which the microporous of the separator can be made non-porous by the influence of the heat when the lithium ion secondary battery generates heat is known. This is expected to stop the conduction of ions in the electrolytic solution and prevent further heat generation and ignition.
• the separator causes a significant shrinkage due to the influence of its heat, and as a result, the conduction of ions in the electrolytic solution cannot be stopped, which may cause a short circuit of the lithium ion secondary battery. ..
• a separator obtained by using a polyolefin resin or the like and having a porous heat-resistant layer provided on the surface thereof is known.
• a porous film containing a polyolefin resin as a main component a multilayer porous film provided with a porous layer containing inorganic particles and a resin binder on at least one surface, wherein the resin binder is one or more monomers selected from (meth) acrylic acid ester monomers.
• a multilayer porous film characterized by being a copolymer containing an unsaturated carboxylic acid monomer and a crosslinkable monomer as a raw material unit is known (see, for example, Patent Document 1).
• this material exhibits a certain effect as a heat-resistant layer, it has insufficient heat resistance in a high-temperature environment such as 180 ° C., and therefore may cause a short circuit of the battery during abnormal heat generation. ..
• An object to be solved by the present invention is to provide an aqueous resin composition for a lithium ion secondary battery separator heat-resistant layer binder having excellent heat-resistant shrinkage.
• the present invention relates to at least one monomer (a2) selected from an acrylic monomer (a1) having an alkyl radical having 4 to 18 carbon atoms, diacetone (meth) acrylamide and N-methylol (meth) acrylamide. ), A radical polymer (A) containing an unsaturated monomer (a3) having a carboxyl group, and an acrylonitrile (a4) as essential raw materials, and a lithium ion secondary battery separator heat-resistant containing an aqueous medium (B).
• a monomer (a2) selected from an acrylic monomer (a1) having an alkyl radical having 4 to 18 carbon atoms, diacetone (meth) acrylamide and N-methylol (meth) acrylamide.
• a radical polymer (A) containing an unsaturated monomer (a3) having a carboxyl group, and an acrylonitrile (a4) as essential raw materials and a lithium ion secondary battery separator heat-resistant containing an aqueous medium (B).
• a water-based resin composition for a layer binder wherein the acrylonitrile (a4) in the monomer raw material of the radical polymer (A) is 5 to 30% by mass, and the heat resistance of the lithium ion secondary battery separator is high. It relates to an aqueous resin composition for a layer binder.
• the aqueous resin composition for a heat-resistant layer binder of a lithium ion secondary battery separator of the present invention can be suitably used as a binder for a heat-resistant layer of a lithium ion secondary battery separator because a separator having excellent heat-resistant shrinkage can be obtained.
• the aqueous resin composition for a heat-resistant layer binder of a lithium ion secondary battery separator of the present invention comprises an acrylic monomer (a1) having an alkyl group having 4 to 18 carbon atoms, diacetone (meth) acrylamide, and N-methylol (meth).
• the acrylic monomer (a1) is an acrylic monomer having an alkyl group having 4 to 18 carbon atoms, and is, for example, n-butyl (meth) acrylate, i-butyl (meth) acrylate, and t-butyl. Examples thereof include (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate. ..
• These acrylic monomers (a1) can be used alone or in combination of two or more. Among these, butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferably used.
• (meth) acrylate means one or both of acrylate and methacrylate
• (meth) acrylamide means one or both of acrylamide and methacrylamide
• (meth) acrylic means one or both of acrylic acid and methacrylic acid
• (meth) acryloyl refers to one or both of acryloyl and methacrylic acid.
• the monomer (a2) is at least one acrylic monomer selected from diacetone (meth) acrylamide and N-methylol (meth) acrylamide.
• the unsaturated monomer (a3) is an unsaturated monomer having a carboxyl group, and is, for example, an unsaturated monocarboxylic acid such as (meth) acrylic acid or crotonic acid, maleic anhydride, maleic acid, or anhydrous.
• unsaturated monocarboxylic acids such as itaconic acid, itaconic acid, and fumaric acid, but (meth) acrylic acid is preferable because the heat shrinkage property is further improved.
• These monomers (a3) may be used alone or in combination of two or more.
• the radical polymer (A) uses the acrylic monomer (a1), the monomer (a2), the unsaturated monomer (a3), and the acrylonitrile (a4) as essential raw materials, but other than these.
• the other monomer (a5) of the above may be used as a monomer raw material.
• Examples of the monomer (a5) include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate and propyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate and 3-hydroxypropyl.
• a monomer having a nitrogen atom such as a monomer having an N-hydroxymethylamide group such as acrylate and (meth) acrylamide and a monomer having an N-alkoxymethylamide group such as N-butoxymethylacrylamide;
• (Meta) acrylate having a glycidyl group such as (meth) acrylate; vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyloxypropyl Monomer having an alkoxysilyl group such as triethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane; polyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxypolypropylene Polyalkylene glycol
• These monomers (a5) may be used alone or in combination of two or more.
• the monomer (a1) in the monomer raw material of the radical polymer (A) is preferably 50 to 80% by mass, more preferably 55 to 75% by mass, because the adhesion to the substrate is further improved. ..
• the monomer (a2) in the monomer raw material of the radical polymer (A) is preferably 1 to 20% by mass, more preferably 3 to 20% by mass, because the heat resistance shrinkage is further improved. 5 to 15% by mass is more preferable.
• the monomer (a3) in the monomer raw material of the radical polymer (A) is preferably 0.5 to 5% by mass, preferably 0.5 to 3% by mass, because the heat shrinkage property is further improved. Is more preferable.
• the amount of acrylonitrile (a4) in the monomer raw material of the radical polymer (A) is 5 to 35% by mass, but 10 to 35% by mass is preferable, and 20 to 35% is preferable because the heat shrinkage property is further improved. More preferably by mass.
• Examples of the method for producing the radical polymer (A) include various methods, but an underwater polymerization method or an emulsion polymerization method is preferable because the radical polymer (A) can be easily obtained.
• the monomer (a1) which is the raw material of the radical polymer (A) is subjected to an emulsifier and polymerization initiation in an aqueous medium.
• an emulsifier and polymerization initiation in an aqueous medium examples thereof include a method of radical polymerization at a temperature of 50 to 100 ° C. in the presence of an agent.
• emulsifier examples include sulfate esters of higher alcohols and salts thereof, alkylbenzene sulfonates, polyoxyethylene alkylphenyl sulfonates, polyoxyethylene alkyl diphenyl ether sulfonates, and sulfate half ester salts of polyoxyethylene alkyl ethers.
• Anionic emulsifiers such as alkyldiphenyl ether disulfonates, dialkyl ester succinate sulfonates; polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene diphenyl ethers, polyoxyethylene-polyoxypropylene block copolymers, Nonionic emulsifiers such as acetylene diols; cationic emulsifiers such as alkylammonium salts; amphoteric emulsifiers such as alkyl (amide) betaine and alkyldimethylamine oxides can be mentioned. These emulsifiers may be used alone or in combination of two or more.
• the monomer (a1) can also be used as an emulsifier.
• polymerization initiator examples include azo compounds such as 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2-methylbutyronitrile), and azobiscyanovaleric acid; tert-butylperoxy.
• Organic compounds such as pivalate, tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexanoate, di-tert-butyl peroxide, cumene hydroperoxide, benzoyl peroxide, and tert-butyl hydroperoxide.
• Oxides Inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate and the like can be mentioned.
• these polymer initiators can be used alone or in combination of two or more. Further, it is preferable to use these polymerization initiators in the range of 0.1 to 10% by mass with respect to the total amount of the monomers which are the raw materials of the polymer.
• the dispersion stability of the radical polymer (A) is further improved, it is preferable to adjust the pH with a basic compound and / or an acidic compound, and examples of the basic compound include methylamine and dimethylamine. , Trimethylamine, ethylamine, diethylamine, triethylamine, 2-aminoethanol, 2-dimethylaminoethanol and other organic amines; inorganic basic compounds such as ammonia (water), sodium hydroxide, potassium hydroxide; tetramethylammonium hydroxide, tetra. Examples thereof include -n-butylammonium hydroxide and quaternary ammonium hydroxide of trimethylbenzylammonium hydroxide. These basic compounds may be used alone or in combination of two or more.
• the acidic compound examples include carboxylic acid compounds such as formic acid, acetic acid, propionic acid and lactic acid; monoesters or diesters of phosphoric acid such as phosphoric acid monomethyl ester and phosphoric acid dimethyl ester; methanesulfonic acid, benzenesulfonic acid and dodecylbenzenesulfonic acid.
• Organic sulfonic acid compounds such as; inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and the like. Of these, carboxylic acid compounds are preferred. These acidic compounds may be used alone or in combination of two or more.
• Examples of the aqueous medium (B) include water, an organic solvent miscible with water, and a mixture thereof.
• the organic solvent to be mixed with water include alcohols such as methanol, ethanol, n-propanol and isopropanol; ketones such as acetone and methyl ethyl ketone; polyalkylene glycols such as ethylene glycol, diethylene glycol and propylene glycol; alkyl ethers of polyalkylene glycol. Examples include lactams such as N-methyl-2-pyrrolidone.
• only water may be used, a mixture of water and an organic solvent miscible with water may be used, or only an organic solvent miscible with water may be used. From the viewpoint of safety and environmental load, water alone or a mixture of water and an organic solvent miscible with water is preferable, and water alone is particularly preferable.
• aqueous medium (B) it is convenient and preferable to use the aqueous medium used for producing the polymer (A) by the underwater polymerization method and the emulsion polymerization method as it is.
• the aqueous resin composition of the present invention contains the radical polymer (A) and the aqueous medium (B), and the radical polymer (A) obtained by an emulsion polymerization method or the like is the aqueous solution. It is preferably dispersed in the medium (B).
• the amount of the organic solvent in the resin composition of the present invention can be reduced by going through a solvent removal step as necessary.
• the aqueous resin composition of the present invention obtained by the above method has a range of 5 to 60% by mass of the radical polymer (A) with respect to the total amount of the aqueous resin composition because the coating workability is further improved. It is preferably contained in the above, and more preferably contained in the range of 10 to 50% by mass.
• the aqueous resin composition of the present invention further improves the coating workability
• the aqueous resin composition contains the aqueous medium (B) in the range of 95 to 40% by mass with respect to the total amount of the aqueous resin composition. It is preferably contained in the range of 90 to 50% by mass, more preferably.
• the aqueous resin composition of the present invention can be used as a curing agent, a curing catalyst, a lubricant, a filler, a thixo-imparting agent, a tackifier, a wax, a heat stabilizer, a light-resistant stabilizer, a fluorescent whitening agent, and foaming, if necessary.
• Additives such as agents, pH adjusters, leveling agents, antigelling agents, dispersion stabilizers, antioxidants, radical trapping agents, heat resistance imparting agents, inorganic fillers, organic fillers, plastics, reinforcing agents, catalysts , Antibacterial agent, Antifungal agent, Anticorrosive agent, Thermoplastic resin, Thermosetting resin, Pigment, Dye, Conductivity imparting agent, Antistatic agent, Moisture permeability improver, Water repellent, Oil repellent, Hollow foam, Crystal water-containing compounds, flame-retardant agents, water-absorbing agents, hygroscopic agents, deodorants, foam stabilizers, antifoaming agents, anticorrosive agents, preservatives, algae-proofing agents, pigment dispersants, blocking inhibitors, hydrolysis inhibitors, Pigments can be used in combination.
• diacetone (meth) acrylamide is used as the monomer (a2)
• the aqueous resin composition of the present invention can obtain a separator having a small heat shrinkage rate, it can be suitably used as a binder for a heat-resistant layer of a lithium ion secondary battery.
• the inorganic filler examples include oxides such as silica, alumina, titania, zirconia, magnesia, zinc oxide and iron oxide, nitrides such as silicon nitride, titanium nitride and boron nitride, silicon carbide, calcium carbonate and magnesium sulfate.
• Aluminum Sulfate, Aluminum Hydroxide, Aluminum Hydroxide, Potassium Titanium, Tarku, Kaolinite, Decite, Nacrite, Halloysite, Pyrophyllite, Montmorillonite, Sericite, Mica, Amesite, Bentnite, Asbestos, Zeolite, Silicic Acid Calcium, magnesium silicate, silicate soil, silica sand, calcined kaolin and the like can be used.
• a separator having communication holes capable of conducting ions can be used in a range where the solid content mass ratio between the inorganic filler and the aqueous resin composition of the present invention is 1 / 1,000 to 1/5. It is preferable to form a separator having excellent heat resistance.
• Example 1 Synthesis and evaluation of aqueous resin composition (1) for lithium ion secondary battery separator heat-resistant layer binder
• aqueous resin composition (1) for lithium ion secondary battery separator heat-resistant layer binder In a 1.0 L reaction vessel equipped with a stirrer, a thermometer and a cooler, and a nitrogen blow, 112.0 parts by mass of ion-exchanged water was charged and heated to 60 ° C., and then 1.0 part by mass of acrylic acid was added to the mixture. 1.
• a mixture of 5.0 parts by mass of N-methylolacrylamide, 60.0 parts by mass of n-butyl acrylate, and 34.0 parts by mass of acrylonitrile was used as an emulsifier (“Hytenol N-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., anionic emulsifier). 5 parts by mass was emulsified with an emulsifying aqueous solution dissolved in 35.5 parts by mass of ion-exchanged water to prepare a monomer premix.
• the heat-resistant layer slurry (1) obtained above was coated on both sides of a polyethylene separator substrate having a thickness of 12 ⁇ m with a bar coater so that the film thickness after drying was 4 ⁇ m to obtain a separator (1).
• the drying temperature was 60 ° C. and the drying time was 5 minutes.
• Example 2 Synthesis and evaluation of aqueous resin composition (2) for lithium ion secondary battery separator heat-resistant layer binder
• aqueous resin composition (2) for lithium ion secondary battery separator heat-resistant layer binder In a 1.0 L reaction vessel equipped with a stirrer, a thermometer and a cooler, and a nitrogen blow, 112.0 parts by mass of ion-exchanged water was charged and heated to 60 ° C., and then 3.0 parts by mass of acrylic acid was added. 1.
• a mixture of 10.0 parts by mass of N-methylolacrylamide, 60.0 parts by mass of n-butyl acrylate, and 27.0 parts by mass of acrylonitrile was used as an emulsifier (“Hytenol N-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., anionic emulsifier). 5 parts by mass was emulsified with an emulsifying aqueous solution dissolved in 35.5 parts by mass of ion-exchanged water to prepare a monomer premix.
• Example 1 except that the aqueous resin composition (1) for the lithium ion secondary battery separator heat-resistant layer binder used in Example 1 was changed to the aqueous resin composition (2) for the lithium ion secondary battery separator heat-resistant layer binder.
• the heat-resistant layer slurry (2) and the separator (2) were prepared by the same operation as in the above, and the heat-resistant shrinkage property was evaluated.
• Example 3 Synthesis and evaluation of aqueous resin composition (3) for lithium ion secondary battery separator heat-resistant layer binder
• aqueous resin composition (3) for lithium ion secondary battery separator heat-resistant layer binder In a 1.0 L reaction vessel equipped with a stirrer, a thermometer and a cooler, and a nitrogen blower, 112.0 parts by mass of ion-exchanged water was charged and heated to 60 ° C., and then 3.0 parts by mass of acrylic acid was added.
• a mixture of 10.0 parts by mass of diacetone acrylamide, 60.0 parts by mass of n-butyl acrylate, and 27.0 parts by mass of acrylonitrile was used as an emulsifier (“Hitenol N-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., anionic emulsifier) 1.5.
• a mass portion was emulsified with an emulsifying aqueous solution dissolved in 35.5 parts by mass of ion-exchanged water to prepare a monomer premix.
• Example 1 except that the aqueous resin composition (1) for the lithium ion secondary battery separator heat-resistant layer binder used in Example 1 was changed to the aqueous resin composition (3) for the lithium ion secondary battery separator heat-resistant layer binder.
• the heat-resistant layer slurry (3) and the separator (3) were prepared by the same operation as in the above, and the heat-resistant shrinkage property was evaluated.
• a mixture of 1.6 parts by mass of acrylamide, 92.8 parts by mass of n-butyl acrylate, and 2.0 parts by mass of acrylonitrile is mixed with 1.5 parts by mass of an emulsifier (“Hytenol N-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., anionic emulsifier).
• an emulsifier (“Hytenol N-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., anionic emulsifier).
• Example 1 except that the aqueous resin composition (1) for the lithium ion secondary battery separator heat-resistant layer binder used in Example 1 was changed to the aqueous resin composition (R1) for the lithium ion secondary battery separator heat-resistant layer binder.
• a heat-resistant layer slurry (R1) and a separator (R1) were prepared by the same operation as in the above, and the heat-resistant shrinkage was evaluated.
• Table 1 shows the evaluation results of Examples 1 to 3 and Comparative Example 1 described above.
• Comparative Example 1 is an example in which the acrylonitrile (a4) in the monomer raw material is less than 5% by mass, which is the lower limit of the present invention, but it has been confirmed that the heat-resistant shrinkage of the obtained heat-resistant layer is inferior. rice field.

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• 2021
  • 2021-05-20 JP JP2022521343A patent/JP7151938B2/ja not_active Ceased
  • 2021-05-20 CN CN202180029561.2A patent/CN115428248A/zh active Pending
  • 2021-05-20 WO PCT/JP2021/019097 patent/WO2021251092A1/ja active Application Filing
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